The invention relates to a circuit arrangement for commutating a reluctance motor comprising a rotor movable relative to a stator and a winding, to which a current is admitted through a switching device in specific positions of the rotor relative to the stator, and including a detection arrangement detecting a voltage induced in the winding and activating the switching device when the induced voltage reaches a predetermined value.
DE-OS 25 56 809 discloses a control circuit for a reluctance motor having variable magnetic conductivity. Herein the reluctance variation is used and, consequently, the variation of the magnetic conductivity of a magnetic circuit running through a motor winding when the rotor rotates relative to the stator. In the circuit the rotation of the rotor furthermore provides also a change of the self-inductance of the motor winding, the self-inductance having a direct ratio to the magnetic conductivity of the magnetic circuit. For energy supply the winding can be connected to a DC voltage source by means of a semiconductor switching circuit. Connected to the motor winding is a switching means through which the electromotive force induced in the motor winding during the rotary motion of the rotor and the blocking state of the semiconductor switching circuit can be detected and the semiconductor switching circuit can be switched through when the detected electromotive force reaches a predetermined value.
U.S. Pat. No. 4,450,396 discloses an electronically controlled synchronous machine having armature and field windings on the same magnetically-permeable core. The self-inductance of the armature and field windings is in essence independent of the relative position of the rotor and the stator in the machine, but mutual inductance between the armature and field windings varies with the relative position. A rotor position detector senses the voltage in one of the machine windings and relates this voltage to said relative position of the rotor and stator. Furthermore, switches are provided to control the electric current flow in the armature winding on the basis of the voltage sensed by the detector. In that Patent a solution is described according to which sensing signals for the relative position of rotor and stator are tapped from the armature windings. For controlling the switches a control means is provided which comprises a microprocessor.